This invention concerns a method for facilitating the removal of pin bones in fish. More particularly, it relates to a method in which the pin bone is cut closest to its outwardly projecting portion, and in which the relatively hard bone portion of the pin bone then may be removed from the fish flesh, whereas the softer cartilage portion of the pin bone may remain in the fish. The invention also comprises a device for carrying out the method.
As known, a vertically and upwardly-directed bone projects out from the dorsal vertebra of a fish, and with respect to the foremost dorsal vertebras, also at least two rib bones encircle the abdominal cavity. In several species of fish, including species of salmon, the foremost dorsal vertebras are also provided with two so-called dorsal ribs projecting substantially horizontally outward in either direction from the dorsal vertebra. Oftentimes the dorsal ribs are described as pin bones.
The pin bone comprises a relatively hard bone portion closest to the dorsal vertebra and a softer cartilaginous portion comprising collagenic fibres closest to its outer end portion. The outer end portion is provided with a relatively large number of threadlike, soft tendons extending from the cartilage portion and out into the fish flesh. These tendons connect the pin bone with the fish flesh in an efficient manner.
When the pin bone is to be removed from the fish flesh during cleaning of fresh fish, said relatively strong connection between the pin bone and the fish flesh causes the pin bone to be torn off in a position along the length thereof, or that some fish flesh is entrained with the pin bone out of the fish. If fish flesh is entrained with the pin bone, this results in lost profits from the fish flesh, opening in the filet and damage within the fish flesh.
To remedy this problem, it is common in the art to cut the fish flesh in a V-shape along the pin bones in order to remove them, or to wait until rigor mortis has abandoned the flesh and then remove them.
To achieve efficient cleaning and fish production, it is desirable to be able to remove the pin bones during the same cleaning process that comprises removal of the other bones of the fish. As such, it is both cumbersome and cost driving to have to store the fish intermediately and then remove the pin bones. It is also undesirable to have to cut the fish flesh along the pin bones in order to remove them, insofar as this causes the fish flesh to be damaged.
Locating the pin bones and the very removal operation may be carried out by means of methods and devices familiar to person skilled in the art and is therefore not described in further detail.
The object of the invention is to remedy or reduce at least one of the disadvantages of prior art.